UNBJ/UNB1
The International GNSS Service Reference Station at the University of New Brunswick
The Department of Geodesy and Geomatics Engineering at the University of New Brunswick runs a continuously operating Javad Legacy GPS/GLONASS receiver situated in Head Hall on the UNB Fredericton campus. Data have been continuously archived since 15 July 2001.
The receiver is fed by a pole-mounted dual-depth RegAnt choke-ring antenna on the roof of Head Hall (UNB Head Hall antennas).
Until 16 August 2006, the station was known as UNB1 with DOMES number 40146S001. On that date, a new antenna adapter was installed between the pole and the antenna to raise the antenna above the newly-installed roof parapet. The IGS and the International Earth Rotation and Reference Frame Service assigned the new site name UNBJ with DOMES number 40146M002. See IGS Mail Message 5406 for further details. UNBJ data is available from 17 August 2006 onwards. UNBJ site log.
Data is collected from this receiver with a 30-second sampling interval and is automatically transferred to the IGS regional data centres at NASA's Goddard Space Flight Center and the Scripps Institute of Oceanography in RINEX-formatted hourly files a few minutes past each hour. A daily file is also transferred shortly after UTC midnight. The data files may be found at other IGS centres such as the ones at the IGS Central Bureau (IGSCB) at the Jet Propulsion Laboratory and at the Korean Astronomy and Space Science Institute. Meteorological data is provided by the UNB2 SuomiNet station.
UNBJ is currently the only IGS GLONASS reference station in Canada and one of only two IGS stations in the Western Hemisphere supplying hourly GLONASS data files. It is one of several continuously operating GPS reference stations in and near the Province of New Brunswick (station map).
The recent performance of UNBJ is displayed on the IGSCB Web site.
The recent performance of UNBJ hourly GPS data is displayed on the GFZ Web site.
UNBJ and UNB1 data may be accessed from:
NASA Goddard Space Flight Center Crustal Dynamics Data Information System (CDDIS)
ftp site:
Daily 30-second Data Files
ftp://cddis.gsfc.nasa.gov/pub/gps/data/daily/yyyy/ddd/yyt,
where
- yyyy is the four-digit year
- ddd is the three-digit day of year
- yy is the two-digit year
- t is the type of file:
- d is Hatanaka-compressed observation data
- g is compressed GLONASS broadcast ephemeris data
- m is compressed meteorological data
- n is compressed GPS broadcast ephemeris data
- o is compressed observation data
- s is compressed observation summary
In the particular subdirectory, select file unbjddd0.yyt.Z for the UNBJ data and unb1ddd0.yyt.Z for the earlier UNB1 data .
All observation, navigation, and met data are stored in UNIX-compressed RINEX
format.
You can find UNB1 data in the gps directory for days between 10 June 2002 (doy 161) and 15 August 2006 (doy 227). For days between 15 July
2001 (doy 196) and 9 June 2002 (doy 160), you can find UNB1 data (GPS+GLONASS) in the ftp://cddis.gsfc.nasa.gov/pub/glonass/data/ GLONASS directory.
Hourly 30-second Data Files
ftp://cddis.gsfc.nasa.gov/pub/gps/data/hourly/yyyy/ddd/hh,
where
- yyyy is the four-digit year
- ddd is the three-digit day of year
- hh is the numeric UTC hour of the day (00, 01, ... 23)
In the particular subdirectory, select file unbjddda.yyd.Z for the UNBJ data and unb1ddda.yyd.Z for the UNB1 data, where "a" represents the hour (a=00, b=01, etc.).
All data are stored in UNIX-compressed and Hatanaka-compressed RINEX format.
Scripps Orbit and Permanent Array Center (SOPAC)
Daily 30-second Data Files
http://sopac.ucsd.edu/cgi-bin/dbDataBySite.cgi
Enter unbj or unb1 for the site code and day(s) of year for which data is required and select file type. Then click on file to download. All data are stored in UNIX-compressed and Hatanaka-compressed RINEX format.
You can find UNB1 data at the SOPAC site for days between 10 June 2002 (doy 161) and 15 August 2006 (doy 227). For days between 15 July 2001 (doy 196) and 9 June 2002 (doy 160), data is available from the CDDIS site.
Hourly 30-second Data Files
ftp://garner.ucsd.edu/pub/nrtdata/yyyy/ddd/hh/, where
- yyyy is the four-digit year
- ddd is the three-digit day of year
- hh is the numeric UTC hour of the day (00, 01, ... 23)
In the particular subdirectory, select file unbjddda.yyd.Z for the UNBJ data
and unbjddda.yyn.Z for the broadcast ephemeris data where "a" represents the
hour (a=00, b=01, etc.).
The hourly GPS data are archived online for three days; after that time, the
data are deleted since files containing a full day's worth of data are
available in the daily GPS data directories. All data are stored in
UNIX-compressed and Hatanaka-compressed RINEX format.
Position of UNBJ
----------------
Site coordinates for UNBJ refer to the virtual marker which coincides with the
on-axis point where the antenna mast meets the adapter. The position of UNBJ ARP
is approximately 0.227 m above UNB1 ARP; there should be no horizontal offset
(see below).
We do not yet have a definitive position for UNBJ due to the short period of
time the "new" station has been in operation. However, a recent position
determination by the Center for Orbit Determination in Europe (CODE) using UNBJ
data from GPS week 1396 (cod13967.snx) is as follows:
X = 1 761 288.076 00 +/- 0.000 26 m
Y = -4 078 238.503 57 +/- 0.000 28 m
Z = 4 561 417.716 49 +/- 0.000 32 m
These coordinates are in the IGb00 reference frame which is virtually identical
to ITRF00. The epoch of the coordinates is 2006:284:43185.0. The errors are
formal estimated solution errors.
Transforming these coordinates to epoch 2004.0 using IGS-estimated velocities
for UNB1 (see below) gives:
X = 1 761 288.123 89 m
Y = -4 078 238.499 86 m
Z = 4 561 417.707 56 m
Converting these coordinates to geodetic coordinates using the WGS84 ellipsoid,
gives:
lat = 45.950 209 098 = 45-57-00.752 753
lon = -66.641 704 745 = -66-38-30.137 082
hgt = 22.7400 m
CODE reports the repeatability of the week 1396 coordinates as 1.54, 1.27, and
4.12 mm in N, E, and U respectively.
Position of UNB1
----------------
Several research centres have processed UNB1 data to obtain accurate coordinates
of the antenna reference point (ARP) = base of antenna (bottom of preamplifier).
The IGS produced weekly and cumulative position solutions which included UNB1.
The IGS cumulative solution IGS06P14.snx for GPS week 1369 gave the following
coordinates for UNB1:
X = 1 761 288.266 85 +/- 0.001 94 m
Y = -4 078 238.546 37 +/- 0.003 31 m
Z = 4 561 417.751 17 +/- 0.003 76 m
with velocities
VX = -0.017 23 +/- 0.000 39 m/yr
VY = -0.001 34 +/- 0.000 52 m/yr
VZ = 0.003 21 +/- 0.000 58 m/yr
These coordinates are in the IGb00 reference frame which is virtually identical
to ITRF00. The epoch of the coordinates is 1998.0.
Updating the coordinates to epoch 2004.0, gives
X = 1 761 288.1635 +/- 0.0030 m
Y = -4 078 238.5544 +/- 0.0045 m
Z = 4 561 417.7705 +/- 0.0051 m
Converting the epoch 2004.0 Cartesian coordinates to geodetic coordinates using
the WGS84 ellipsoid, gives
lat = 45.950 209 066 = 45-57-00.752 638 +/- 4.7 mm
lon = -66.641 704 555 = -66-38-30.136 398 +/- 1.9 mm
hgt = 22.8309 m +/- 4.8 mm
For further information about UNBJ or UNB1, please contact Hyunho Rho or Richard Langley.
Updated 4 February 2008.
